Selective cut-out for alternating-current circuits.



P. ACKERMAN. SELECTIVE CUT-OUT FOR ALTERNATING CURRENT CIRCUITS. APPLICATION FILED MT -17.1912.

Patented July 25, 1916.

W/TNCJSIS.

A /A i; 5

UNITED STATES PATENT OFFICE.

PAUL ACKERMAN, 0F TORONTO, ONTARIO, CANADA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO GENERAL ELECTRIC COI-IIPANY, A CORPORATION OF NEW YORK.

SELECTIVE CUT-OUT FOR ALTERNATING-CURRENT CIRCUITS.

Application filed October 17, 1912.

To all whom it may concern:

Be it known that I, PAUL AGKERMAN, of the city of Toronto, in the county of York, in the Province of Ontario, Canada, have invented certain new and useful Improvements in Selective Cut-Outs for Altermating-Current Circuits, of which the following is the specification.

My invention relates to improvements in selective cut-outs for alternating current cir cuits and the object of the invention is to provide a reliable and positive means for automatically preventing a reverse energy flow in the faulty feeder or transmission line of a system of distribution comprising a number of feeders or transmission lines in parallel. To this end, I provide for each transmission line two or more differentially wound relays each having one coil energized by current derived from the line to be protected and the other coil energized by current derived from another one of the transmission lines, and so connected that when all of the coils act conjointly to operate the relays the automatic circuit breaker will be tripped to open the circuit through the transmission line. The relays act conjointly when a fault develops of such a character that there is a reversal of energy flow through the transmission line and conse quently through the coils of the relays, all the relays connected to the line act conjointly and trip the circuit breaker. The faulty transmission line or feeder is automatically selected and cut ofi' from the system as soon as the direction of energy flow in the line reverses.

The drawing represents a diagrammatic view of my apparatus showing the various circuits, switches and operating means for a single phase system of parallel feed wires with the automatic reverse current cut out provided for every one of the feed wires.

In the drawings like letters of reference indicate corresponding parts in each figure.

A A and A are a series of alternating generators connected in parallel by transmission lines or feeders.

A and A are feed wires extending from the generator A A and A are feed wires extending from the generator A A and A are feed wires extending from the generator A B, B and B are the primary coils of a Specification of Letters Patent.

Patented July 25, 1916.

Serial No. 726,292.

current transformer located in the feed wires A, A and A respectively.

C and C are bus wires, the feed wires A, A and A leading to the bus wire 0 and the feed wires A A and A leading to the bus wire C In the transmission line or feeder there is an automatic circuit breaker. In the particular form shown D and D are circuit breaker contacts located in the feed wire A.

D and D are circuit breaker contacts located in the feed wire A, and D and D are circuit breaker contacts located in the feed wire A".

E is a movable bridging contact connecting the contacts D and D E is a movable bridging contact connecting the contacts D and D E is a movable bridging contact connecting the contacts D and D It will be understood that the movable bridging contacts E, E and E are normally, as shown in the drawing, in positionto keep the circuit closed.

F is a battery.

F and F are wires leading from the bat tery terminals.

F F and F are branch battery circuits extending from the wires F and F in proximity to each of the feed wires A, A and A F is an operating or trip coil located in the branch battery circuit F 3 and designed to open when energized the circuit breaker E.

F and F 8 are similar trip coils for controlling the circuit breakers E E The branch circuit F 3 is provided with a pair of switch contacts 2 and 3, and a pair of switch contacts 4 and 5. The branch circuit F is provided with a pair of switch contacts 6 and 7 and a pair of switch contacts 7 L and 8, and the branch circuit F is provided with a pair of switch contacts 9 and 1G and a pair of switch contacts 11 and 12. These contacts are normally open so as to break the respective branch battery circuit.

13 is a closing contact designed to bridge the contacts 2 and 3.

14 is a closing contact designed to bridge the contacts 4 and 5.

15 is a closing contact designed to bridge the contacts 6 and 7.

16 is a closing contact designed to bridge the contacts 7 and 8.

17 is a closing contact designed to bridge the contacts 9 and 10, and 18 is a closing contact designed to bridge the contacts 11 and 12.

Each closing contact- 13, 14, 15, 16, 17, and 18 is provided with a movable operating solenoid core 19.

H. 11 and H are the secondary coils of a current transformer located in the feed wires A, A. and A H is an upper current coil surrounding the solenoid core 19 of the closing contact 13.

H is a current coil surrounding the solenoid core 19 of the closing contact 11.

H is a lower current coil surrounding the solenoid core 19 of the closing contact 16 and H is a lower current coil surround ing the solenoid core 19 ot' the closing contact 18.

ll is a circuit wire leading from the secondary coil H of the current transformer through the coil ll, coil H coi H and coil H back to the other terminal of the secondary coil H.

H is an upper current coil surrounding the solenoid core 19 ot' the closing contact15.

H is a current coil surrounding the solenoid core 19 of the closing contact 16.

H is a lower current coil surrounding the solenoid core 19 of tae closing contact 17 and H" is a current coil surrounding the solenoid core 19 of the closing contact 13.

H is a circuit wire leading from one terminal ot' the secondary coil H of the current transformer located in the feed wire A. This circuit extends through the coil H, coil H coil H coil H back to the other terminal of the secondary coil H H is an upper current coil surrounding the solenoid core 19 of the closing contact 17.

H is an upper current coil surrounding the solenoid core 19 of the closing contact 18.

H is a lower current coil surrounding the solenoid core 19 of the closing contact 15.

H is a current coil surrounding the solenoid core 19 of the closing contact 1-1.

H is a wire leading from the secondary coil H through the current coils H H 11 and H back to the other terminal of the secondary coil H 1 and 1 are wires leading from the bus wires C and C to a distributing system.

Having described the principal parts in volved in my invention 1 will briefly describe the operation of the same. The current in the feed wires A A and A is assumed to flow in the direction of arrow from the alternating current generators A 11 and Ar: For the sake of illustration a shortcircuit is assumed to occur at the point indicated by dotted line 16 connecting the feed wires A and it making necessary to open the circuit breaker to maintain a nor mal condition in the distributing system. It

will be readily understood that such a short circuit will result in a momentary current passing through the feed wire 1"! and primary coil B in a reverse direction to the normal flow. This will induce a similar current in the secondary coil i l. It will also be understood that the two coils 01 each relay are ditl erentially wound, so that the normal. flow of current through each of the upper current coils H H H, ii", ii and H is in an opposite direction to the lower current coils ll", H ll, H and H and H thereby holding the closing contacts 13, 11, 15, 16, 17 and 18 in the open position. As soon as the current flow is reversed in one of the teed wires, the current in the secondary coil of the corresponding current transtmrmer will reverse also, thus reversing the current in all current coils in series with that secondary coil. For instance, as above described, the current in the feed wire A is reversed by a short circuit, the current in the coils H H, H will then reverse and there'rore close the corresponding contacts 2, 3, 1 and 5, and 7 8, 11 and 12. This has the effect of closing the branch battery circuit F and opening the circuit breaker E of the faulty feed wire by the coil F. At the same time the other two circuit breakers of the two remaining feed wires are left closed to maintain an uninterrupted service over the wires I, 1 to the distributing system. It will be readily understood that'a similar result will occur should the short circuit occur between the feed wire 11 and A or A and 11 cutting out the faulty teed wire.

I am aware that the battery circuit closure has been in use before for operating the circuit breaker, such closure having solenoids with two current coils making contacts by lifting a solenoid core upon reversal of the current in one element or a torque developing instrument consisting of two current elements making contact upon reversal of current in one of the elements to change the direction of movement of the revolving part. But in both these devices for the battery circuit one current element was ted from a current transformer while the other element was fed from a potential transformer. it rill be readily understood that such a device is most unreliable for the reason that the current in the potential coil may drop to a Zero point under complete short circuit conditions, and would, therefore, tail to operate the closure instantaneously at a low reversal current.

In my device all current coils operating the closures of the battery currents are fed from current transformers and will, therefore operate the closure instantaneously and under all circumstances.

It will be understood that any other source of electromotive force could be used instead of the battery for actuating the release coil of the circuit breaker.

It is further understood that the device shown can be used for any alternating system of multiple phases in applying the same arrangement properly for corresponding phases of parallel feeders.

It is further understood that the same device can be applied to any additional parallel feeder in making a similar combination of the feeder with any two parallel feeders.

It is further understood that for operation of the switches of the battery cir-' cuit any device could be applied which is' operated by two current elements and which will close the switch upon reversal of the current in one of the current elements. And finally it will be understood that my device is only operated by a reverse current flow and not by a straight overload.

From this description it will be seen that I have devised a very simple device whereby a circuit breaker is operated when a short circuit and consequent reverse current occurs in the feed wire, by utilizing only the currents of current transformers, making its operating positive and reliable at all times and under all circumstances.

Thus it will be seen that the tripping of any circuit breaker is dependent on the operation of two sections of a composite relay each portion of which is supplied by series transformers controlled by different feeders, and that the circuit will not be opened except by the conjoint operation of the two sections one coil system of which is supplied by one feeder and the other by another feeder of the system.

That I claim as my invention is 1. Means for opening a defective feeder of an alternating current supply system upon reversal of energy flow, comprising a plurality of series transformers, in difl'erent feeders, each having its primary winding in series with its feeder, a pair of relays and a circuit-breaker for each feeder, each relay having differential coils one of which is supplied by the secondary of the transformer of the feeder which it governs, and the other by different transformers of the other feeders, and a tripping circuit including both of the relay contacts and trip coil of the circuit-breaker, whereby upon a fault in any feeder its circuit will be opened.

2. In a system of distribution comprising transmission lines in parallel and means in each line for deriving a current from said line, means for opening a defective line comprising an automatic circuit breaker and tripping mechanism for said circuit breaker comprising two pairs of differential coils, one coil of each pair being energized by current derived from the defective line, and the other coil of each pair being energized by 'with'said relay armatures to cause conjoint action of sald armatures to trip the circuit breaker, a pair of differential coils for each relay armature, and a series transformer in each circuit of the group supplying current to one coil of each of its own relays and to one'coil only'of each pair corresponding to the other circuits of the group.

I 4. In a system of distribution for alternating currents, means for selectively opening any defective circuit of a group, comprising a circuit-breaker, two differential relays for each circuit, two contacts in series controlled by the relay armatures, a source of trip current adapted to operate any trip coil when both contacts are closed, and a series transformer in each circuit supplying a coil of each of the relays controlling the circuit in which it is interposed and a coil of a relay of another circuit.

5. In a reverse current operated out out, the combination with a series of feed wires leading from a suitable current supply, of a circuit breaker located in one feed wire, a suitably energized circuit breaker operating means and a circuit leading therethrough, a pair of open switches having contacts located in the circuit breaker operating circuit in series with the circuit breaker operating means, a current transformer comprising a primary coil located in one feed Wire and a secondary coil, a pair of electro-magnetic operating means for each switch closure one means of each pair being energized from the secondary transformer coil of one feed wire, the other means of one pair being energized from the second feed wire of the series and the other means of the other pair being energized from the third feed wire of the series whereby one means of each pair normally neutralizes the other means to hold the switches open and whereby each pair of means cooperate together to simultaneously close the switches upon the current being reversed in one means of each pair by the reversal of the current in the first feed wire thereby closing circuit breaker operating circuit and opening current breaker, and independently close the switch closures by the reversal of the current in the other means of either pair by the reversal of the current in the second or third feed wires whereby the circuit breaker operating means is kept open and the circuit breaker closed, as and for the purpose specified.

6. In a system of distribution for alternating currents, a plurality of feeders, a

series transformer and a circuit breaker for each feeder, a pair of relays for tripping each circuit breaker, means for connecting the relay contacts associated With each circuit breaker so that conjoint action of the relay armatures will actuate the trip coil of the circuit breaker, and a pair of differential coils on each relay, one coil of each pair being derived from the series transformer of one feeder and the other from the transformer of another feeder.

T. The combination with a plurality of parallel transmission lines of a plurality of difi'erential relays for each line, each relay having an armature and two opposing Windings for actuating said armature, one Winding of each relay being responsive to current in the line and connected in series with the corresponding Winding of the other relays for said line, and the other Winding of each relay being responsive to current in a different one of said transmission lines, a circuit breaker in each line and means for ca using the conjoint action of the arinatures of the relays for said line to trip said circuit breaker.

PAUL ACKERB'IAN. \Vitnesses B. Born,

M. EGAN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, .D. G. 

